Mothers take part in a protest in Mexico City on May 10. / Ronaldo Schemidt, AFP/Getty Images

by David Agren, Special for USA TODAY

by David Agren, Special for USA TODAY

MEXICO CITY -- Maria Elena Salazar has searched tirelessly for her son, Hugo Marcelino Gonz√°lez, who disappeared one morning 3 1/2 years ago while heading to his technical support job in the northern Mexican city of Torreon.

No ransom demand was ever made. The mother of three says authorities have shown little interest in finding Hugo, who was 24 when he vanished.

So she like many other parents in Mexico carry out their own searches in the hope that they can provide to police some clues about what happened to their loved ones in a country where tens of thousands of people are missing in the wars against drug cartels.

"We've done the investigation," she says. "The case file is thick now, but it's all information we've provided."

Hundreds of mothers like Salazar and the relatives of missing persons marched through central Mexico City on Friday, marking Mexican Mother's Day ‚?? an event considered almost sacred south of the border ‚?? with demands that the federal government take the cases of their loved ones seriously.

Some of the protesters also started hunger strikes to demand action.

Salazar's son is among 27,000 people to vanish in Mexico since the federal government ‚?? led by then-President Felipe Calderon ‚?? cracked down on drug cartels and criminal groups in December 2006. Many migrants heading for the United States also have disappeared, according to the operators of shelters for the hoards of Central Americans transiting Mexico without proper papers.

"It's a powerful signal that there is much more uncertainty than their should be in society toward the authorities," said Bishop Ra√ļl Vera L√≥pez, whose northern Mexico diocese has supported the families of missing persons. "We can't just leave these women (to search) on their own."

Searches for the missing by the authorities have been scant. Salazar says many families suffer from suspicions that their loved ones were somehow involved in illegal activities. But the plight of the missing in Mexico is now moving to the front pages as the country comes to grips with the legacy of a drug war that has claimed close to 70,000 lives, according to the Interior Ministry.

It's still uncertain how many of the disappearances were related to organized crime or people missing for unrelated reasons. A recent report by Human Rights Watch documents 249 cases of forced disappearances that were attributable to the actions of police or soldiers.

"In cases where state agents work with organized crime in carrying out disappearances ‚?¶ security forces arbitrarily detain victims and then hand them over to criminal groups," the report said.

President Enrique Pe√Īa Nieto pledges to reduce crimes such as kidnapping and extortion, but his government has largely stayed silent on the issue of organized crime and violence.

Interior Ministry Miguel √Āngel Osorio Chong has promised that the problem of missing persons will be taken seriously. The new administration also enacted a new "victims' law," which gives those impacted by organized crime some redress.

Family members often have few clues to follow in a disappearance. Many suspect their relatives may have been forcibly recruited into the ranks of organized crime.

Alma Garc√≠a, an adviser to the Fray Juan Larios Human Rights Center in Saltillo south of the U.S. border at Laredo, Texas, says many of the missing persons were employed and some were professionals with skills sought by cartels such as Los Zetas, which operates in the region and carries out crimes like kidnapping.

"All of the northeast of Mexico has been plagued by disappearances," she said of a region rife with crimes carried by cartels.

State investigators, she adds, pass over some cases if they suspect organized crime involvement, leaving them to the federal attorney general's office.

"They say that they're investigating, but where are the results?" asks Lizeth Cardona Mart√≠nez, 19, whose father disappeared three years ago with 11 others while selling paint door-to-door in the border city of Piedras Negras, opposite Eagle Pass, Texas.

"Supposedly there are witnesses, but they don't want to talk. Nobody does."

Families of the missing say they still have some hope that the new government might bring a sense of urgency to their cases, but they expect to be carrying out their own investigations for the foreseeable future.